1. Technical Field
The present invention relates to a vehicle occupant protection apparatus including an inflatable vehicle occupant protection device, such as an air bag. In particular, the present invention relates to an air bag module in which inflation fluid is selectively vented from a housing of the module in order to control the speed and force of deployment of the air bag.
2. Description of the Prior Art
It is known to inflate an air bag to help protect a vehicle occupant in the event of sudden deceleration such as occurs in a vehicle collision. The air bag is stored in a deflated condition, together with an inflator, in a housing adjacent to the vehicle seat in which the occupant sits. The inflator, when actuated, provides a large volume of inflation fluid to inflate the air bag into a position to help protect the vehicle occupant.
Under normal circumstances, substantially all of the inflation fluid from the inflator is directed into the air bag to inflate the air bag. In some circumstances, however, it may be desirable to control or limit the amount of inflation fluid directed into the air bag. For example, if the vehicle occupant is smaller than a predetermined size or is closer to the vehicle instrument panel than a predetermined distance, then it may be desirable to reduce the speed and force with which the air bag inflates. It is known to vent inflation fluid from the housing of an air bag module in such circumstances, so that less inflation fluid is directed into the air bag.
The present invention is a vehicle occupant protection apparatus. The apparatus includes an inflatable vehicle occupant protection device, an inflation fluid source, a housing, a door, and an energizable means. The inflatable vehicle occupant protection device has a deflated condition and an inflated condition for helping to protect the vehicle occupant. The inflation fluid source is actuatable to provide inflation fluid to inflate the inflatable device. The housing directs inflation fluid under pressure from the inflation fluid source toward the inflatable device upon actuation of the inflation fluid source. The housing further has an opening for enabling flow of inflation fluid out of the housing and away from the inflatable device. The door is movable between a closed condition closing the opening and an open condition enabling flow of inflation fluid out of the housing through the opening. The energizable means retains the door in the closed condition and, when energized, enables movement of the door from the closed condition to the open condition in response to fluid pressure in the housing. The energizable means comprises an electromagnet.